This invention is related to a process and a device producing a disturbance in the transmission of the electromagnetic radiation generated by a source within a predetermined wavelength band and designed for interception by a receiver intended to detect signals located within said band.
It more specifically relates to systems where the generator is a body of any kind emitting heat and hence infrared radiation and the detector is a camera or a telescope working in at least one predetermined band of the infrared spectrum.
Nowadays infrared cameras are utilized in a wide range of civil and military applications in order to detect, to locate and to pursue fixed or moving objects via an analysis of their infrared emitting spectrum. In this way, the infrared radiation of a vehicle engine or of an aircraft or missile mover is detected readily. This technique is the only now available operational means to detect and to pursue missiles and to guide localizing missiles at long distances up to 10,000 km. For detection purposes, several infrared bands supply specific information commonly linked to the temperature differences in the bodies under consideration and it is commonly admitted nowadays that it is becoming difficult to pursue any surface activity that could not be detected by the analysis of the infrared radiation, said analysis being eventually made in real time by an infrared telescope on board a satellite in geostationary orbit provided with a discriminator and a high speed computer.
The disadvantage of the infrared radiation lies in a substantial atmospheric absorption but there is a propagation window in earth atmosphere with a wavelength comprised between 3 and 5 micrometers. For this reason and other important technological reasons, the best multi-spectra infrared cameras work in the wavelength band comprised between 2.2 and 8 micrometers.
Nowadays the only countermeasures available toward the detection, localizing and pursue by means of an analysis of the spectrum of any infrared radiation are the use of baits, the artificial increase of atmosphere density and the remote disturbance of infrared pick up electronic circuits. Baits are easily identified by improved discriminators, while the other two countermeasures are difficult to be implemented and are not operational at present.